Method of and apparatus for producing transparent waxed paper



May 6, 1930. J. DECKER METHOD OF AND APPARATUS FOR PRODUCING TRANSPARENT WAXED PAPER Original Filed Feb. 9, 1927 Lzzvenia 7 19. ciaknjecJoer cfir'kza' .ZVZaaez 'wr Patented May 6, 1930 UNITED STATES P ATENT OFFICE.

JOHN DECKER AND ARTHUR B. GREEN, OF MIDDLETOWN, OHIO, AND VASCO E. NUNEZ, OF NASHUA, NEW HAMPSHIRE, ASSIGNORS TO NASHUA GUMMED & COATED PAPER COMPANY, OF NASHUA, NEW HAMPSHIRE, A CORPORATION OF MASSACHUSETTS METHOD OF AND APPARATUS FOR PRODUCING TRANSPARENT WAXED PAPER Application filed February 9, 1927, Seria1'No. 167,027. Renewed March 10, 1930.

This invention relates to the production of waxed paper in such a condition of transparency as to enhance its utility for such purposes as the wrapping of boxes orcartons which bear printed matter that should be easily readable through the wrapping. We do not limit ourselves however to said par ticular use for the paper.

In carrying out our invention we subject paper which is coated or impregnated with wax such as parafline, to the direct action of heat at a temperature sufliciently high to change the crystal structure of the wax so as to effect an increase in the index of refraction or, in other words, to increase the optical continuity of the wax and paper fiber, and so produce wax paper which presents no mott-led appearance. As hereinafter explained, it is desirable for some purposes to make certain additions to the wax.

Parafiine Wax, even after subjecting it to the temperature-necessary to place it in condition for impregnating or coating paper with it, has a crystalline structure and contains very minute particles of air. The principal object of our invention is to effect such degree of penetration of the wax into the paper, and to effect such changes in the orientation of the molecules of the wax and in the crystal structure of the wax-which is carried by the paper or with which the paper is impregnated, and to. effect such expulsion or combustion of the air in the wax, as to increase the optical continuity of the wax and I the paper fibers. We attain this object by subjecting the coated or impregnated paper to a degree of heat and for a length of time but little short of causing combustion, and

then slowly cooling the wax and paper.

Of the accompanying drawings v Figure 1 is a somewhat conventional illustration of one form of apparatus for carrying out our method, said figure representing a longitudinal section through the apparatus to the pinch rolls 17.

omitting framing and other non-essential parts.

Figure 2 is a similar view of a slightly dif-.

ferent apparatus.

Similar reference characters indicate simi-' 25, 1915, and 1,429,928, dated September 26,

1922, both issued to W.

L. Carter, and Letters Patent 1,385,042 issued July 19, 1921 to Decker and VanSluys, it will be suflicient for present purposes to' refer to those patents for illustration of suitable framework to support the various rolls and other parts of the apparatus[ Referring first to Figure 1, the web of paper a is drawn from a supply coil or roll mounted on a shaft or spindle 12, and passes over a guide roll 13 and is immersedin melted wax in a pan 14 which, for our improved purposes, is preferably lead-lined or enamelled and must be kept clean. The wax is kept in melted condition by any suitable means such as referred to in the above-mentioned,pate nts.

An important feature of our present invention is that instead of effecting a single As illustrated, there are two of such rolls and the paper, after passing under one of them,

passes over a steam-heated roll 16, then under the second immersion or dip roll 15,, and then v over a second steam-heated rollglfi, on its way This arrangement pro vides for contact of both surfaces of the paper with heated rolls, first one surface and then the other. The rolls 17, which are relatively adjustable as usual, squeeze out the excess of wax and thus control the weight of the finished paper.

therefore acting' on both surfaces of thepa er.

11 its way-from the pinch rolls 17 to the rolls 20, the paper-is subjected to an intense heat uniformly applied to the entire .area thereof, and this forms the most essential portion of our invention, the importance thereof being presently explained. The means illustrated for so heating the waxed paper comprises an extended area or set of gas burners 18, desirably protected against fire hazard by a suitable hood or baflle member conventionally illustrated at 19.

The subsequent treatment of the paper after it leaves the rolls 20 includes a relatively slow cooling operation, and may include burnishing by rolls 21, from which the paper travels some little distance exposed to the atmosphere, and then in contact with a plurality of cooling rolls 22, and is then wound on a shaft or core 23. In order that the cooling operation may be gradual or stepped down, it is preferable that the means for controlling the tempartures of the rolls 22 (of which there may be more than the two illustrated) shall be such that the paper contacts withrolls of successively lower temperatures.

The apparatus illustrated by Figure 2 is substantially the same as hereinbefore described, with the exception that instead of the cooling rolls 22, or in addition thereto, a cold water bath is employed, with means for quickly removing the water from the paper after it leaves said bath. In said Figure 2 the paper is illustrated as passingfrom the steam-heated 'rolls 20 over a guide roll 24,

then vertically between burnishing rolls 21, then under two guide rolls 25 immersed in water in a tank 26, suitable refrigerating coils 27 being employed for maintaining the water at a chilling temperature. From the cold water bath the paper passes upward between a series of wipers or scrapers 28, over an upper roll 29, and then down between suction pipes 30, then under a guide roll 31 to the winding or coiling shaft 23. Asthe wipers 28 and suction pipes 30 are, or may be, the same as" illustrated and described in Letters Patent No. 1,385,042 hereinbefore referred to, detailed illustration and description thereof herein are unnecessary.

In carrying out our method with either form of apparatus illustrated, or by any equivalent means, it is preferable that heating flames be employed, and that said flames contact directly with the waxed paper, the latter travelling at suflicient speed to prevent the wax or the paper from becoming ignited.

is maintained, by electricity or otherwise, at

a sufliciently high point to so change the crystal structure of the wax as to effect the desired transparency. And of course we do not limit ourselves to subjecting the paper to heat applied to but one side thereof, as the paper may travel between two heaters. In any event, it is desirable that the heat employed be such as to bring the wax almost to the point of ignition, and to then cool the wax and paper rather slowly.

As illustrated in both figures of the drawings, there is nothing over which the paper travels while being heated and with which the paper can contact. In other words, the paper is unsupported while over the heating element. Therefore, there is nothing with which the paper can so contact as to cause mottling or streaking.

The advantage of'employing flames contacting with the waxed paper is that the air, which is present in minute globules in paraffine wax and which detracts from dsirable transparency of the wax and paper, is consumed by the flames, or is expelled therefrom. This is largely aided by the fact that the paper, when passing directly over theflames or, if desired, between flames on opposite sides thereof, is practically shut off from the access of free air.

So far aswve are aware this exclusion of air 1s an entirely new result. Another new result which could not be expected from any former practice of making waxed paper, is the effect on the appearance of the paper to the eye. All waxed paper is and has been more transparent than plain paper, but it has always had a mottled appearance which not only detracts from a high degree of transparency but also has a cloudy appearance. The paper produced according to the present invention however is practically free from any visually perceptible mottled appearance and is more transparent than heretofore known waxed paper.

It is a fact. also that there is a coaction in obtaining the best results as to transparency, between the double dip of the web a in the wax in tank 14 and the subsequent submission of' the latter of which act on both surfaces of the waxed web. Among the advanta es of the structure just referred to is thoroug and uniform combining of the wax with the paper, and consequent uniform transparency.

We have found that transparency of the waxed paper may be enhanced by the use of addition agents. For instance this object is attained by adding to the melted wax in the tank a-smal1 percentage of a metallic soap such as aluminum stearate or a small proportion of a suitable dye such as methyl blue, or by adding both or certain nitrogenous organic compounds.

Such modification of the crystal structure of the wax may be obtained by such additions because it is known that certain dyes are readily absorbed by the fibers of the paper and serve as an orienting bond between fibers and paraflin molecules; also that they regularize crystal sizes; also that a slight bluish cast gives to the eye an optical effect of greater transparency. Metal soaps, such as aluminum stearate, sodiumoleate etc., have a favorable action, due to serving as a bonding agent with the fibers of the paper.

Having now described our invention, we claim 1. A machine for producing waxed paper free from mottling and having a high degree of transparency, said machine including a waxing tank, means for causing a web of paperto travel through said tank, and means 7 for applying to the paper as it leaves said tank a degree of heat but little short of causing combustion.

2. The method of treating waxed paper to increase its transparency and avoid a mottled appearance thereof, said method consisting in subjecting said paper to a degree of heat but little short of causing combustion, and then cooling the wax and paper.

3. The method of rendering waxed paper transparent, consisting in subjecting said paper while unsupported to the direct action of flames.

4. The method of rendering waxed paper transparent, consisting in subjecting said paper wihle unsuppor ed to the action of heat but little short of causing combustion of the paper.

5. The method of enhancing the transparency of waxed paper, consisting in refining the crystal structure of the wax by the direct application of heat thereto at a temperature but little short of causing combustion of the paper.

6. The method of producing transparent waxed paper, said method consisting in causing a web of uncoated paper to pass a plurality of times through melted wax, and then subjecting the waxed paper to the action of a degree of heat but little short of causing combustion of the paper.

7. The method of producing transparent waxed paper, said method consisting in mix-' in g a modifying agent with the wax, immersing the paper in the modified and melted wax, and then directly subjecting the waxed paper to a high degree of heat but little short of causing combustion of the paper.

8. A machine for producing transparent waxed paper, said machine including a waxing tank, and means for causing a web of paper to travel first through said waxing tankleaves said tank an intense heat but little short.

of causing combustion of the paper.

In testimony whereof we have afiixed our signatures.

JOHN DECKER. ARTHUR B. GREEN. VASCO E. NUNEZ. 

